I need to pass about ~0.01mA at ~4V through a diode at high efficiency. (that's 10uA, folks)

What I would look at would be a diode with a low forward drop. Perhaps a Schottky type? I imagine this is for your micro-power harvesting project? I would be surprised if you ended up with very high efficiency there.There's also the question of reverse leakage. If you have 10 uA forward, and the diode leaks 25 uA in reverse, then I don't think you're going to get much rectification out of it...

Turns out there are energy harvesting IC's specifically for stuff like this lol . . .

Yes, absolutely! There are even full boards you can plug into your source on one end, your battery on the other, and it's done.Where on the spectrum of "eating ice cream" vs "milking a cow" do you want to fall?

Where on the spectrum of "eating ice cream" vs "milking a cow" do you want to fall?

pardon?

How much of a ready product are you looking for? You can buy assembled battery-and-generator-and-harvester packs off the shelf. You can buy the parts and plug them together. You can buy the ICs and make your own PCB. Or you can design and build your own from discrete components.

Are you looking to get a working energy harvester to use in a project? Then buy a ready-made one! Are you looking to solve a design challenge? Then build your own starting with raw silicon crystals :-) Or do you have a particular reason to fall in the middle of that spectrum, where you won't just buy one off the shelf?